The invention relates to a method for managing the display of a rotary indicator. Embodiments of the invention have an advantageous application in aeronautics for the display, on an instrument panel of an aircraft, of the value of the altitude and/or of the speed of the aircraft.
More precisely, most aircraft are equipped with combined instruments generally used as standby and displaying the attitude of the aircraft in a central zone, the speed in a left lateral zone and the altitude in a right lateral zone.
Mechanical indicators have been used for displaying the speed and the altitude in combined standby instruments. Such an indicator makes several juxtaposed wheels rotate about a horizontal axis. Each wheel allows the display of a character which is generally alphanumeric. All of the values that a character can have are printed on each wheel. While rotating, the wheels move vertically in front of a window in order to allow only the current value of the speed or of the altitude to appear. To ensure good legibility of the current value, the height of the window should be sufficient for there always to be one character entirely visible in the window whatever the position of the wheel may be. In order to satisfy this criterion, the height of the window should be at least equal to twice the height of a character plus the height of the spacing between two successive characters.
Digital displays have appeared in combined instruments but, in order not to disturb aircraft pilots, these new displays have retained the same presentation of information as in the mechanical instruments.
The window forms part of the display device of a navigation instrument on which other information is displayed and there is a tendency to reduce the size of the window to allow the display of a greater amount of data on the display device. In order to reduce the size of the window whilst retaining good legibility, it has been attempted to retain the height of the characters and to reduce the spacing between characters. It has also been attempted to reduce the height of the characters whilst retaining the spacing. These two solutions have not been ergonomically satisfactory.